Olympics: 'Medical tape' row as record-breaking Danish pursuit team accused of bending UCI rules

rjfrussell wrote:

https://www.scientificamerican.com/article/how-do-dimples-in-golf-ba/

 

Nice one! We just need to keep an eye out now for riders with dimpled legs....

I reckon that London 2012 French complaint about "magic wheels" was a mishearing, and they were just pointing out that the Brits were riding (nominally French) Mavic wheels.

Awavey wrote:

Can anyone explain in layman's terms just how a bit of plaster is in anyway aiding aerodynamics more than an average shin ?

counterintuitively perfectly smooth surfaces are not aerodynamically efficient. air flow will hug the surface, while a rough surface will create eddies pulling air away from the surface reducing resistance.

Hence golf balls have dimples, without which there would be more friction, which would be randomnly assymetric leading to random flight paths.

But human legs are naturally not perfectly smooth as an aero surface to begin with, so they are literally putting a sticking plaster on something to correct for something they dont need to do if the end result is make your legs a bit less smooth.

Half of me thinks it's a version of kinesiology tape to deal with shin splints, the other is kidding all the other teams into focusing on something that makes no difference at all,like rounder wheels.

Awavey wrote:

But human legs are naturally not perfectly smooth as an aero surface to begin with, so they are literally putting a sticking plaster on something to correct for something they dont need to do if the end result is make your legs a bit less smooth. Half of me thinks it's a version of kinesiology tape to deal with shin splints, the other is kidding all the other teams into focusing on something that makes no difference at all,like rounder wheels.

skin is a lor closer to smooth the the trip from the tape.

certainly not shin splints as all riders have the same tape.

certainly the bluff may be a factor

Hence why I don't shave my legs 😂

HLaB wrote:

Hence why I don't shave my legs 😂

I don't have to - my wife keeps pointing out that I used to have hairy legs...  The hair on my legs disappeared a couple of years ago and never grew back...

wycombewheeler wrote:

Awavey wrote:

Can anyone explain in layman's terms just how a bit of plaster is in anyway aiding aerodynamics more than an average shin ?

counterintuitively perfectly smooth surfaces are not aerodynamically efficient. air flow will hug the surface, while a rough surface will create eddies pulling air away from the surface reducing resistance.

Hence golf balls have dimples, without which there would be more friction, which would be randomnly assymetric leading to random flight paths.

Are you sure about that? Planes tend to be quite smooth, and I understand a lot of effort (≡ cost) is taken to ensure the paint is suitably so. (PS not being arsey, complex aero is not my major)

The dimples on golf balls create lift. A golf ball is imparted bottom spin when it is hit by a standard club. When spinning the dimples help to drag the air over the top (fast air = low pressure), whilst pushing it in the opposite direction of travel underneath the ball (this increases air pressure). Hey presto, lift. In fact were the dimpled surface more aero dynamic than a smooth surface, the lift would not be generated to the same degree, and a smooth surface would be prefered.

The effect is real. When golf balls were made of wood it was observed that a used one would fly further, due to the nicks and dents. apparently, the effect also stabilises the ball, but Mr Fox (my A level Physics teacher, ace rowing coach, and a regular caution) didn't get to that bit.

Golf ball dimples reduce drag so they go further.

planes wings are aerofoils which are very aerodynamic but also produce lift due to high and low pressure

this tape will provide a little trip to make the air turbulent to reduce the drag of the riders top of sock to below knee area

check12 wrote:

Golf ball dimples reduce drag so they go further.

....

I like Mr Fox's explanation better...

Captain Badger wrote:

Are you sure about that? Planes tend to be quite smooth, and I understand a lot of effort (≡ cost) is taken to ensure the paint is suitably so. (PS not being arsey, complex aero is not my major)

quite important to keep the laminar flow over the wing if you want lift, I would think. Why the fusilage is not dimpled is another question.

Captain Badger wrote:

The dimples on golf balls create lift. A golf ball is imparted bottom spin when it is hit by a standard club. When spinning the dimples help to drag the air over the top (fast air = low pressure), whilst pushing it in the opposite direction of travel underneath the ball (this increases air pressure). Hey presto, lift. In fact were the dimpled surface more aero dynamic than a smooth surface, the lift would not be generated to the same degree, and a smooth surface would be prefered.

The effect is real. When golf balls were made of wood it was observed that a used one would fly further, due to the nicks and dents. apparently, the effect also stabilises the ball, but Mr Fox (my A level Physics teacher, ace rowing coach, and a regular caution) didn't get to that bit.

Hmm, certainly something here, and not necesarily just about creating lift, but also creating predictible resistance. I know they have found as thy made footballs smoother, that a slowly rotating ball can swerve in unpredictable ways as any minor blemish on the ball can cause a significant effect and can move from the right to the left during the shot, while a quickly spinning ball will curve predictably. 

The spinning ball will curve towards the side of the ball moving slower, in the same way you describe lift froma golf ball.

The point remains that air flowing smoothly along the side of a surface will create more drag than air caused to seperate.

However I know a little more about flow of liquids in pipes which may be laminar (all liquid flowing parallel to the pipe walls) or turbulent. You would think that the chaos of turbulent flow would lose more energy than smooth laminar flow, but at the transition from laminar to turbulent there will be a reduction, before the friction losses increase as the flow becomes more turbulent.

Perhaps the far greater velocities of planes move the friction beyond the early reduction of dragging along the smoth sides 

wycombewheeler wrote:

The point remains that air flowing smoothly along the side of a surface will create more drag than air caused to seperate.

And that may be so as a standard principle to start from, but we are still lacking the explanation of how that specifically applies to a leg that is not just travelling forward through airflow, but is simultaneously rapidly moving up & down, which is not what either golf ball or a plane wing does.

And that in that pedalling movement creates such a aerodynamically draggy effect, TeamGB have designed bikes with specific forks to compensate.

And we are positing the Danish went nah just stick a bit of tape on your leg there, because golf balls.

Even Dr Hutch, who again uses golf balls to stand up this theory, admits he tried it 10 years ago but couldnt get it to work on the road.

Anyway they didnt use it today.

Awavey wrote:

...Anyway they didnt use it today.

Cos they know we're on their case. We've got 'em rattled people....

wycombewheeler wrote:

......

quite important to keep the laminar flow over the wing if you want lift, I would think. Why the fusilage is not dimpled is another question.

Captain Badger wrote:

The dimples on golf balls create lift. A golf ball is imparted bottom spin when it is hit by a standard club. When spinning the dimples help to drag the air over the top (fast air = low pressure), whilst pushing it in the opposite direction of travel underneath the ball (this increases air pressure). Hey presto, lift. In fact were the dimpled surface more aero dynamic than a smooth surface, the lift would not be generated to the same degree, and a smooth surface would be prefered.

The effect is real. When golf balls were made of wood it was observed that a used one would fly further, due to the nicks and dents. apparently, the effect also stabilises the ball, but Mr Fox (my A level Physics teacher, ace rowing coach, and a regular caution) didn't get to that bit.

Hmm, certainly something here, and not necesarily just about creating lift, but also creating predictible resistance. I know they have found as thy made footballs smoother, that a slowly rotating ball can swerve in unpredictable ways as any minor blemish on the ball can cause a significant effect and can move from the right to the left during the shot, while a quickly spinning ball will curve predictably. 

The spinning ball will curve towards the side of the ball moving slower, in the same way you describe lift froma golf ball.

The point remains that air flowing smoothly along the side of a surface will create more drag than air caused to seperate.

However I know a little more about flow of liquids in pipes which may be laminar (all liquid flowing parallel to the pipe walls) or turbulent. You would think that the chaos of turbulent flow would lose more energy than smooth laminar flow, but at the transition from laminar to turbulent there will be a reduction, before the friction losses increase as the flow becomes more turbulent.

Perhaps the far greater velocities of planes move the friction beyond the early reduction of dragging along the smoth sides 

rjf posted the link to a Scientific American article (no paywall) above which was absolutely fascinating.

The increased drag on a smooth ball is a result of an increased wake apparently. That and the lift generated from the spin are both components of teh improved performance of a dimpled ball.

Love this kind of thing

wycombewheeler wrote:

Awavey wrote:

Can anyone explain in layman's terms just how a bit of plaster is in anyway aiding aerodynamics more than an average shin ?

counterintuitively perfectly smooth surfaces are not aerodynamically efficient. air flow will hug the surface, while a rough surface will create eddies pulling air away from the surface reducing resistance.

Hence golf balls have dimples, without which there would be more friction, which would be randomnly assymetric leading to random flight paths.

Dependent on Reynolds Number, but essentially yet.

kil0ran wrote:

Might just be that the suits are particularly translucent this year but I noticed a fair few riders with rosin marks on the front/tops of their shoulders. In fact, a lot more rosin use than I've seen for a while. Anything to rough up the airflow a little?

Isn't rosin the stuff they rub on violins/cellos/double basses' strings?

brooksby wrote:

Isn't rosin the stuff they rub on violins/cellos/double basses' strings?

Almost. It's rubbed on the bow hairs - it eventually deposits onto the strings, but then has to be cleaned off

"Items of clothing may not modify the morphology of the rider and any non-essential element or device, of which the purpose is not exclusively that of clothing or protection, is forbidden."

It is a very badly drafted rule, because it combines too quite different things in one sentence, but it seems to me pretty clear that the meaning is:

A- clothing that modifies morphology is forbidden

B- any "element or device" that is not exclusively clothing or protection is also forbidden.

There is then C- the ruling on sruface roughness to clothing which is not engaged here. 

There is no morphology requirement for non-clothing elements or devices.

So, unless it can be said that the exclusive purpose of the tape is clothing (obviously not) or "protection" (perhaps arguable- but protection from what?) then the tape is forbidden.  The fact that it does not alter the morphology and/or is less than 1mm thick is irrelevant.

Agree with that. If the 'and' were read as applying to both morphology and non-essential element/device in order to be forbidden they would likely be ok. But the first 'may not' knackers that argument. 

Agree - I don't want to disparage people but whoever took that quote from Lizzie Banks really should have asked what bit of the skin she thinks is clothing.

Whilst the first para. as you rightly say, combines two concepts that are similar but not the same at least potentially confusingly, but the surface roughness provisions are entirely unambiguous and clearly only apply to clothing!

Finally, I would make the additional point that I'm not sure I'd agree that tape doesn't alter the morphology of the body. Whilst it is subtle, surface morphology is a thing and changing the textures on the surface it seems at least arguably alters the structure, at a minute level, of the surface of the skin.

rjfrussell wrote:

"Items of clothing may not modify the morphology of the rider and any non-essential element or device, of which the purpose is not exclusively that of clothing or protection, is forbidden."

It is a very badly drafted rule, because it combines too quite different things in one sentence, but it seems to me pretty clear that the meaning is:

A- clothing that modifies morphology is forbidden

B- any "element or device" that is not exclusively clothing or protection is also forbidden.

There is then C- the ruling on sruface roughness to clothing which is not engaged here. 

There is no morphology requirement for non-clothing elements or devices.

So, unless it can be said that the exclusive purpose of the tape is clothing (obviously not) or "protection" (perhaps arguable- but protection from what?) then the tape is forbidden.  The fact that it does not alter the morphology and/or is less than 1mm thick is irrelevant.

Indeed the 1mm is specifically limited to threading, weaving or assembling the fabric.

So if the material has a 0.9mm surface roughness, then OK, or if the seams result in 0.9mm ridges then ok. but sticking tape to an otherwise functional piece of clothing does not seem within the rules. UNLESS the tape is holding the suit together. But since the tape is applied to the shins it is clearly not part of the fabric or the joinging of the fabric. 

anyway all smacks of the "super round wheels" team GB had in 2012.

Possibly the most British thing to do - let's NOT hire one of the most innovative cyclists and thinkers about cycling aerodynamics and tactician, who just happened to win the National Championships beating the British Cycling Team Pursuit Squad and also winning a couple of rounds of the Track Cycling World Cup.